How does the tsunami warning system work?

Seismographs can recognize earthquakes or volcanic eruptions - which can cause tsunamis. But only a few large earthquakes cause this size event, so the warning system based only on seismic data is easily alarmed.

Scientists need to add other devices at sea to assist in identification. They include 2 main types: Pressure gauges at the bottom of the sea and tide gauges - sea level monitoring on the coast.

Dart warning system.
1. The receiver at the bottom of the sea measures water pressure every 15 seconds.
2. The float measures surface conditions and sends it with the seabed data to the satellite.
3. Satellite receives data and sends it to ground station.

Ocean Tsunami and Tsunami Warning System (Dart) uses buoys and probes that are located far from the sea.

A pressure gauge at the bottom of the sea will measure the height of the water above it - change the wave height - and send a signal to a float on the surface. This float monitors the surface condition and sends the information it receives - plus data from the sea floor - to a satellite, where they are relayed back to a ground receiving station.

Germany is cooperating with Indonesia in a project to place 10 buoys in this Indian Ocean region. The first two were installed last November. India, Thailand and Australia are also expected to install Dart buoys along the Sunda Trench - the area that triggered the earthquake, triggering the tsunami of December 26 last year.

Tide gauge
1. The tube in the tube will measure sea level.
2. Data is processed and sent to satellite.
3. Satellite data transmission to the alert center.

The advantage of the Dart system is that it can detect tsunamis far from the sea and have enough time to warn countries in the region. However, the cost of installing and operating buoys is very expensive.

Meanwhile, the UNESCO Intergovernmental Oceanographic Commission (IOC) is focusing on a network of tidal or sea level gauges.

Unlike Dart buoys, tide gauges in the Global Sea Level Observation System (GLOSS) are located on land - either on the shores of large continents or on offshore islands. The most basic type of gauge observes the surface of the water with a pipe and float system. More modern designs "shoot" radars or ultrasound waves into the water from above, or use sea floor pressure sensors attached to a surface observation station with a cable.

There are nearly 70 GLOSS stations in the Indian Ocean. Before the tsunami last year, they were used to measure sea level in long-term studies of climate change, and data was only transmitted periodically. But now they are upgraded to send instant information via satellites to newly established national tsunami warning centers.